The invention concerns a vehicle wheel and, in particular, a wheel having special sound absorbing properties.
When a vehicle travels over a road, its driver and passengers are placed in the passenger space in a very noisy environment. It is a constant concern of automobile manufacturers to limit the sound level of their vehicles as much as possible.
The sources of these noises in the passenger space are highly varied. They include noises due to the engine, or of aerodynamic origin, or linked to the various hydraulic pumps or running noises of the tires on the road.
The latter originate from shocks sustained on rolling by the tire treads and solidly transmitted to the vehicle passenger space. Such noises come within a very wide frequency range of between 80 and 800 Hz, with, notably, peaks toward 250 Hz. These noises are called "body hum."
In this frequency range, one encounters, in particular, a natural mode of vibration of the air toroid of the inner cavity of the tire as well as four natural modes of vibration of ordinary wheels.
A great deal of research has been undertaken to try to limit the noise heard in the passenger space of vehicles. For example, patent application JP 4-87803 proposes introducing a wall in the inner cavity of the tire in order to divide the inner air toroid in two, substantially altering its modes of vibration by shifting them beyond 500 Hz and thus lower the peaks of the body hum in the passenger space at around 250 Hz.
Another mode of action is described in application JP 6-106903. This application proposes inserting a sound absorbing element in the inner cavity of the tire, such as a foam, in order to attenuate the vibrations due to resonance of the air toroid.
These applications have not yet been put to any industrial use to date; consequently, the problem of effectively reducing the noise heard in the passenger space of a vehicle is still very much present.